1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and a computer program product.
2. Description of the Related Art
Recent digital copy machines are also called digital multifunction peripheral (MFP) because they are able to exert copy function for copying a document and multiple functions such as scanner function, printer function, facsimile (FAX) function and the like. Such a digital MFP is used with a local area network (LAN) for a use of scanner function and printer function, and is often connected to an external network to exert facsimile function. Furthermore, output data from the scanner function and printer function is stored in a mass-storage device such as hard disk drive (HDD) disposed in the apparatus. Therefore, it is easy to transmit image data stored in the HDD via a network, or to store image data received from the external into the HDD.
The manner in which MFP is used in office is also diversified. For example, a small-sized MFP is often placed with personal computer (PC) to allow a user to use the functions of copy, facsimile, printer, and scanner in a convenient manner; a medium-sized MFP which is shared by a plurality of persons in a particular division or section to realize some productivity and use of sorting, punching, stapling and the like functions; and a large-sized MFP with various functions realizing high productivity and high quality used in a division that concentratedly conducts copy associated business in enterprise, or in a company specialized in copy associated business are known.
However, some functions can be shared by different classes (the small, the medium, and the large-sized MFPs), while other functions are exclusively necessary in a particular class. For example, in a large-sized MFP, it is necessary to conduct post processing on sheet after plotting image data or to conduct electronic filing concurrently with copying operation. Examples of the post processing include punching, stapling, and folding. On the other hand, in a small-sized MFP, improvement in internet FAX or PC-FAX and high quality image printing onto special sheet are demanded for personal use purpose.
Because importance of information value in business has been recognized, it is increasingly required to transmit information quickly, accurately, and reliably, in an easy-to-understand manner and in an effective manner. Speeding up and prevalence of communication technique, enlarged capacity, reduced cost, and reduced size of memory, and increased performance of PC are associated with provision of new functions for efficiently handling information with digital data, and provision and incorporation of such new functions are also demanded for MFPs which handle digital image data.
Data is output from an MFP to a sheet as is the case of copying, and transmitted as electronic data as is the case of scanner and FAX transmission, as described above. For transmitting electronic data, output formants can be changed depending on the use application. For example, in FAX transmission, monochrome binary image data format is used, while in a scanner transmission, color RGB image data is used.
As described above, an MFP outputs image data from various units having different output characteristic. In the case of output to paper, characteristic of a writing unit and in the case of scanner delivery, characteristic of a display on which the data is to be displayed are exemplified. In an MFP, a mass storage device such as HDD is provided. It is also possible to accumulate image data read by a scanner or image data from external in the storage device. And the accumulated image data may be re-outputted to a sheet or used for data communication via a FAX in a similar manner as the image data is accumulated.
A conventional MFP having a function as describe above is disclosed in Japanese Patent Application Laid-Open No. 2001-223828, Japanese Patent Application Laid-Open No. 2001-251522, and Japanese Patent Publication No. 3741090.
When information containing image data is processed, in particular, when image information is processed, data is temporarily stored in a storage device because data volume is large, and only data to be processed is read out from the storage device at the time of processing to execute intended processing. As a storage device, HDD is generally used. Although HDD has a large capacity, its capacity has limitation in accumulating data. For example, if an image of A3:600 dots per inch (dpi):RGB is stored in a storage unit, its image size becomes 200 megabytes or larger, which is too large to be stored in the HDD. For this reason, it is general to accumulate image data by compressing the image data at the time of accumulation.
As for a compression format, a lossy compression format such as Joint Photographic Experts Group (JPEG) may be used. However, size after JPEG compression varies depending on the imaged data. In particular, data compressibility is different between the case where image data with skin is compressed and the case where image data without skin is compressed. Therefore, when accumulated image data is large, capacity of HDD is used up. Furthermore, removing the skin in advance to reduce image size is inappropriate when the skin needs to be outputted with an image.